C÷C-C-C
1-2-3-4 (left to right)
The ÷ represents the triple bond.
C1 is triple bonded to C2, as well as bonded to a H.
C2 is triple bonded to C1, as well as bonded to C3.
C3 is bonded to 2 H's, as well as C2 and C4.
C4 is bonded to C3, as well as 3 H's.
(Hope this helps, it's difficult to make a diagram on phone).
